Method of treating cellulose derivative material and product thereof



Patented Apr. 4, 1933 CAMILLE DREYFUS, OF NEW YORK, N. Y.,

AND HERBERT PLATT, OF CUMBERLAND,

MARYLAND, ASSIGNORS TO CELANESE CORPORATION OF AMERICA, A CORPORATION 01 DELAWARE METHOD OF TREATING CELLULOSE DERIVATIVE MATERIAL AND PRODUCT THEREOF No Drawing.

This invention relates to the treatment of material containing derivatives of cellulose and particularly to the treatment of textile materials containing yarns of organic esters of cellulose to impart stiffness to the same.

An object of our invention is to impart stiflness to material containing derivatives of cellulose, and particularly organic esters of cellulose, by subjecting the same to a reagent that tends to stiffen the same. Other objects of our invention will appear from the following detailed description.

In accordance with our invention, we impart stiffness to materials, and particularly textile materials, containing suitable derivatives of cellulose, by subjecting the same to the action of strong sulfuric acid for a suitable period of time, and then removing the acid from the material.

The material to be treated may contain any suitable derivative of cellulose. This derivative. of cellulose may be an inorganic derivative of cellulose such as cellulose nitrate but preferably it is an organic ester of cellulose such as cellulose acetate, cellulose formate, cellulose propionate or cellulose butyrate,

The material to be treated may be in any suitable form. Thus it may be fabric containing yarns made of derivatives of cellulose, such as cellulose acetate. The material may be treated in the form of yarn wound in suitable packages such as hanks, bobbins and the like and the yarns stiffened by our process may be Woven or constructed into any suitable fabric. Anotherapplication of our invention is in the imparting of stiffness to heavy filaments, in order to produce bristles or artificial horse-hair containing a derivative of cellulose such as cellulose acetate. Another application of our invention is in stiffening artificial straw, films, sheets or other articles containing the derivatives of cellulose with or without plastifiers and filling material.

The reagent employed for stiffening material is preferably strong sulfuric acid, say

from 40 to 80% or more concentration. This strong sulfuric acid may contain water as the diluent but often the presence of organic acid such as acetic acid or inorganic acid such as Application filed April 16,

1929. Serial No. 355,657.

hydrochloric acid produces beneficial effects. The time of treatment of the material with the strong sulfuric acid is preferably short, say from 5 to 30 seconds or more. After treatment with the strong sulfuric acid, the acid is removed such asby washing with water and treatment with a weak alkaline solution such as weak solutions of sodium hydroxide or ammonium hydroxide. As to the temperatures, we have found that ordinary room temperatures are quite suitable, although higher or lower temperatures may be employed. Generally, for a given concentration of acid and time of treatment, the higher the temperatures, the greater the degree of stiffness imparted.

The degree of stiffness imparted to the cellulose derivative material may be varied by varying the strength of the sulfuric acid and/or the time of treatment. The weaker the sulfuric acid employed the less stiffness will be imparted, While the longer the time of treatment, the greater will be the degree of stiffness.

The material treated in accordance with our invention has a stiffness imparted thereto, which stiffness is substantially unimpaired by repeated subsequent laundering, which is quite surprising.

Our invention lends itself to many applications. Thus if a fabric containing cellulose acetate yarn of fine construction, say of voile, is treated by our invention, a permanent organdie effect is obtained. If a coarser fabric is subjected to our process, the resultant stiff fabric may be used as a stiffening material in the construction of garments or other wearing apparel as is known in the art. When bristles are treated by our invention, such stiffness is imparted to them to make them highly useful for use in the construction of brushes of various kinds.

We have found that if the organic ester material is partially saponified, the action of the strong sulfuric acid is not as great upon the partially saponified material so that the stiffness imparted thereto is not so great. Therefore, the amount of stiffness imparted to a textile material containing an organic ester of cellulose such as cellulose acetate may be controlled by partially saponifying the same to the desired extent priorto treatment with the sulfuric acid. Furthermore differential effects may be obtained by locally partially saponifying a textile material such as a fabric made of an organic ester of cellulose and then treating with the strong sulfuric acid. This differential efiect may also be obtained by the local application of printing or other paste that act as resists to the sulfuric acid.

In order further to illustrate our invention but without being limited thereto, the following specific example is given.

Emample A voile consisting wholly of cellulose acetate yarn is immersed in an aqueous solu- .tion of sulfuric acid of 83 Tw. (51%) at room temperatures. The time of treatment is 9 seconds, and the fabric is then immediately washed in water and then may be treated in a neutralizing'solution containing 2 cc. of ammonia water per litre. The fabric thus treated is stiffened and it has the handle and feel of a high class organdie. This material retains its stifiness after repeated washing and laundering, and its strength is in no way impaired.

It is to be understood that the foregoing detailed description is given merely as an illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we claim and desire to secure by Letters Patent 1s:

1. Process of imparting stifi'ness to textile materials containing esters of cellulose comprising partially saponifying the cellulose ester and then subjecting the textile material to the action of strong sulfuric acid, whereby the amount of stiffness imparted will be controlled by the degree of partial saponification of the cellulose ester.

2. Process of imparting stiffness to textile materials containing cellulose acetate comprising partially saponifying the cellulose acetate and then subjecting the material to the action of strong sulfuric acid, whereby the amount of stiffness imparted will be controlled by the degree of partial saponification of the cellulose acetate.

3. Process of locally imparting stiffness to textile materials containing esters of cellulose comprising partially saponifyin the cellulose ester locally and then subjecting the textile material to the action of strong sulfuric acid, whereby the parts not partially saponified are stifi'er than the parts partially saponified.

4. Process of locally imparting stiffness to textile materials containing cellulose acetate comprising partially saponifying the cellulose acetate locally and then subjecting the textile material to the action of strong sulfuric acid, whereby the parts not partially saponified are stifier than the parts partially saponified.

5. Process of stiffening bristles containing cellulose esters comprising artially saponif ing the cellulose ester and then subjectin t e same to the action of strong sulfuric aci whereby the amount of stiffness imparted will be controlled by the degree of partial saponification of the cellulose ester.

6. Process of stiffening bristles containing cellulose acetate comprising partially saponifying the cellulose acetate and then subjecting the same to the action of stron sulfuric acid, whereby the amount of sti ness imparted will be controlled by the degree of partial saponification of the cellulose acetate. In testimony whereof, we have hereunto subscribed our names.

CAMILLE DREYFUS. HERBERT PLATT. 

